Carbon-supported Ni and NiCo catalysts have been prepared for amino compound electrooxidation. Their electrocatalytic behaviors toward 8 kinds of amino acids (glycine, alanine, histidine, methionine, proline, serine, tyrosine, and cysteine) were investigated via electrochemical methods and in situ Raman spectroscopy. The Ni and NiCo catalysts demonstrated catalytic activity for amino acid electrooxidation, and the current densities differ according to the R side chain group. Compared to Ni/C, NiCo/C is superior in terms of onset potential and anodic current density. Electrochemical in situ Raman characterization indicated that NixCo1–xOOH was generated above the onset potential. The amino compounds were electrooxidized after the onset potential by the NixCo1–xOOH active species. However, the anodic current of cysteine was observed at a more negative potential than the onset potential, caused by the electrooxidation of sulfur in the R side chain. A direct alkaline fuel cell was fabricated with glycine as the fuel. The fuel cell with NiCo/C anode catalyst achieved a maximum power density of 3.0 mW cm−2 at 60 °C, 1.5 times higher than that of the fuel cell with the Ni/C anode catalyst.
Yucheng Li,Jing Liu,Jing He,Luying Wang,Jiandu Lei
The effect of titanium as a promoter for the nickel-cobalt/silica-titania (NiCo/Si-Ti) catalyst in the hydrogenation of phenol was comparatively studied. In the phenol hydrogenation under mild reaction conditions (1 MPa H 2 pressure and 100 °C), the Ti-promoter induces the formation of the Co δ− −O V −Ti 3+ active sites and enhances the hydrogenation activity of the NiCo/Si catalyst to convert phenol to cyclohexanol. The catalytic hydrogenation with the optimal composition of the NiCo/Si-1.0Ti (Si:Ti ratio of 8.5:1) catalyst was completed within 1 h (conversion 98.2 % and selectivity >99 %), which was more efficiently than that with other Ti-doped catalysts and NiCo/Si as baseline, indicating a strong positive synergistic effect between the metal (Ni-Co) and support (Ti-Si) components of the catalyst in this reaction. Additionally, the kinetics, pathway and catalytic mechanism of the hydrogenation of phenol are also examined. Furthermore, the NiCo/Si-1.0Ti catalysts also showed a good performance at reducing the unstable oxygenated compounds in the bio-oil.
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